Multiple cathode indicator tube having improved anode and mercury source

ABSTRACT

An indicator tube having a stack of cathodes and a cylindrical anode enclosing the stack of cathodes. The anode includes a rear plate and a front screen. The rear anode plate is provided with at least one projecting finger which extends toward the cathodes and facilitates cathode glow, and an annular mercury capsule is secured to the rear surface of the anode plate by means of metal tabs.

Inventor Richard B. F ehnel Basking Ridge, NJ.

Appl. No. 813,257

Filed Apr. 3, 1969 Patented Jan. 26, 1971 Assignee Burroughs Corporation Detroit, Mich. a corporation of Michigan MULTIPLE CATHODE INDICATOR TUBE HAVING IMPROVED ANODE AND MERCURY SOURCE [56] References Cited UNITED STATES PATENTS 1,817,445 8/1931 Robinson 313/174X 3,230,027 1/1966 Mayer 313/174X 3,244,923 5/1966 Milliken 313/1095 3,318,649 5/1967 Keller, Sr. et a1. 3 l3/l09.5X

Primary Examiner-John Kominski Assistant Examiner-David OReilly Attorneys-Kenneth L. Miller and Robert A. Green 7 Claims, 9 Drawing Figs.

US. Cl 313/ 109.5, ABSTRACT: An indicator tube having a stack of cathodes 313/174, 313/177, 313/217 and a cylindrical anode enclosing the stack of cathodes. The Int. Cl ..H01j 61/24, anode includes a rear plate and a front screen. The rear anode HOlk 7/04 plate is provided with at least one projecting finger which ex- Field of Search 313/1095, tends toward the cathodes and facilitates cathode glow, and an 174, 177, 179, 205, 206, 210, 217, 251, 251.1, annular mercury capsule is secured to the rear surface of the 309, 356 anode plate by means of metal tabs.

l l l I I2 l I f z I70 0 I. I// v MULTIPLE c Taope NnrcAroR,TunEnAvrNo IMPROVED ANODE AND MERCURY SOURCE BACKGRO UNDOF THE INVENTION Multiple cathode indicator tubes have been known for many years, and through the years, there has been a constant trend toward miniaturization. As the tubes have become smaller, it has become more and more difficulttoprovide. suitable locations and toachieve secure mounting for all of its components. The mercury capsule .is one ofthese problem components. The mercury, capsule is a metalgor glass container which is mounted in'the tube envelope and carries the.

DESCRIPTION OFTHE DRAWING FIG. I is a perspective view of a tubeembodying the invention; I 7' FIG. 2 is a side elevational view, partly in section, of a por-v tion of the tube of FIG. 1;

FIG. 3 is a plan view of a portion of the tube of FIG. 1;

FIG. 4 is a plan view of a modification of the anode electrode shown in FIG. 3; 5

FIG. 5 is a plan view of another modification of the anode electrode; I

FIG. 6 is an elevational view of a portion of the structure shown in FIG. 2;

FIG. 7 is a sectional view along the lines 7-7 in FIG. 6;

FIG. 8 isa sectional view showing a modification of the portion of the tube shown in FIG. 7,; and

FIG. 9 is a sectional view showing anothermodification of the portion of the tube shown in FIG.;7.

DESCRIPTION OF THEPREFERRED EMBODIMENTS An indicator tube 10 embodyingthe invention is shown as a, side viewtube and includes an envelope '20 having a flat dome 30, a viewing window 40,.tnd a stemSiO. The envelope insuitably secured to the anode assembly tobe described. The cathodes have lower tabs which are secured to tube pins 100.

which extend through the stem of the envelope.

The anode assembly in tube 10 comprises a rear anode plate and a frontanode screen 120, the screen and plate comprising a tubular anode which encloses the stack of cathodes.

The front screen and rear plate 110 are welded together at their side edges, and their lower ends rest on the stem. The plate and screen are also secured to tube pinsfor mechanical support and to permit the application of voltages thereto. The rear I anode plate may be curved (FIG. 3), or it may have curved side panels' and a flat rear panel 140, (FIG. 4), or it may have that side panels and a flat rear panel (FIG:

5), the panels 150 and 160 being at angles to each other. The front screen may also be completely curved, or it may have fiat portions. 1 1

In order to improve anode operation, particularly with respect to thecathode electrode at the rear of the stack, the inner surface of the anode plate is provided with one or more projecting-fingers whichcxtendtoward the lust cathode at the rear of the stack. The projecting fingers may be formed by metallic tabs-or rods welded to the rear plate, or they may be formed by punching tabs out of the rear anode plate and bending them toward-the cathodes. Preferably, a series of fingers 170 are provided arranged in a vertical column and extending from top to bottom alongthe central vertical axis of the anode plate.

Thetube 10 also includes auxiliary cathode electrodes inthe form of decimal points, commas, or any other character. Eachauxiliary electrode is secured to a tube pin and is suitably positioned in the tube with respect to the numeral cathodes.

Accordingto the invention, a mercury capsule 200 is provided which compfises a metallic ring having a suitable recess in which aquantity of mercury 20! in a suitable binder is carriedThe capsule 200is of relatively large diameter and small thickness and is'secured to the rear surface of the rear anode plate! I0 in any suitable fashion. In one arrangement, the-ring capsule-200 is held in place by tabs 210 which are welded to the anode'plate or are punched out ofthe anode plate and are bent over the ring to hold the ring against the anode plate. Two or more such tabs are provided.

In one'embodiment of the invention which provides particularly good support for the mercury ring, an annular depression 220 (FIG. 8)is formed in the rear surface of the anode plate, and the'ring is held in place in this depression by the tabs 210.

The depression may also'be shaped as shown in FIG. 7 so that it includes an annular trough 230 in which the ring fits and a central projection 240 which enters the central opening of thecapsule ring.

In still another arrangement (FIG. 9), the anode plate 110 is provided with abutton 250 which rises above the rear surface of the anode plate andenters the central opening of the annular capsule.

During'the manufacture of tube l0, mercury is released from the ring capsule 200'by heat generated therein, for example, by means of aradio frequency heating coil positioned adjacent to the capsule, as is well known in the art.

I claim:

1. A multiple cathodegas-filled display tube comprising:

an envelope filled with a gas capable of sustaining cathode glow;

said envelope having'a dome at its upper end and a stem at its lower endand a viewing window between the dome and stem; 5

an electrode assembly in said envelope including a stack of cathode electrodes facing said viewing window and a cylindrical anode enclosing said stack of cathodes; saidvanode electrode including a rear anode plate and a front anode screen; and said rear anode plate having at least one projecting finger extendingtoward the last cathode at the rear of the stack of cathodes to facilitate the initiation of glow of said last cathode. 2. The tube defined in claim 1 wherein said rear anode plate includes a plurality of said projecting fingers extending toward said last cathode.

3. The tube defined in claim 2 wherein a plurality of said projecting fingers are provided extending vertically from top to bottom of said'rearanode plate and oriented along the vertical axis thereof. j

4. A multiple cathode gas-filled display tube comprising:

an envelope filled with a gas capable of sustaining cathode glow;

said envelope having a dome at its upper end and a stem at its lower end and a viewing window between the dome and stem;

an electrode assembly in said envelope including a stack of cathode electrodes facing said viewing window and a cylindrical anode enclosing said stack of cathodes;

said anode electrode'including a rear anode plate and a front anode-screenjand vided with an annular depression in which said capsule is seated and secured.

7. The tube defined in claim 4 wherein said capsule is secured to said rear anode plate by a plurality of tabs carried by said rear anode plate and engaging said capsule. 

2. The tube defined in claim 1 wherein said rear anode plate includes a plurality of said projecting fingers extending toward said last cathode.
 3. The tube defined in claim 2 wherein a plurality of said projecting fingers are provided extending vertically from top to bottom of said rear anode plate and orientEd along the vertical axis thereof.
 4. A multiple cathode gas-filled display tube comprising: an envelope filled with a gas capable of sustaining cathode glow; said envelope having a dome at its upper end and a stem at its lower end and a viewing window between the dome and stem; an electrode assembly in said envelope including a stack of cathode electrodes facing said viewing window and a cylindrical anode enclosing said stack of cathodes; said anode electrode including a rear anode plate and a front anode screen; and a capsule containing a substance to be released into the atmosphere in said envelope, said capsule being secured to said rear anode plate.
 5. The tube defined in claim 4 wherein said rear anode plate includes a depression in which said capsule is seated.
 6. The tube defined in claim 4 wherein said capsule is a metal ring and the rear surface of said rear anode plate is provided with an annular depression in which said capsule is seated and secured.
 7. The tube defined in claim 4 wherein said capsule is secured to said rear anode plate by a plurality of tabs carried by said rear anode plate and engaging said capsule. 